Surfactant solutions distributions

Similar spatial distribution of active bubbles has been observed in partially degassed water and in pure water irradiated with pulsed ultrasound [67]. For both the cases, the number of large inactive bubbles is smaller than that in pure water saturated with air under continuous ultrasound, which is similar to the case of a surfactant solution. As a result, enhancement in sonochemical reaction rate (rate of oxidants production) in partially degassed water and in pure water irradiated with pulsed ultrasound has been experimentally observed [70, 71]. With regard to the enhancement by pulsed ultrasound, a residual acoustic field during the pulse-off time is also important [71]. 

An aqueous dispersion of a disperse dye contains an equilibrium distribution of solid dye particles of various sizes. Dyeing takes place from a saturated solution, which is maintained in this state by the presence of undissolved particles of dye. As dyeing proceeds, the smallest insoluble particles dissolve at a rate appropriate to maintain this saturated solution. Only the smallest moieties present, single molecules and dimers, are capable of becoming absorbed by cellulose acetate or polyester fibres. A recent study of three representative Cl Disperse dyes, namely the nitrodiphenylamine Yellow 42 (3.49), the monoazo Red 118 (3.50) and the anthraquinone Violet 26 (3.51), demonstrated that aggregation of dye molecules dissolved in aqueous surfactant solutions does not proceed beyond dimerisation. The proportion present as dimers reached a maximum at a surfactant dye molar ratio of 2 5 for all three dyes, implying the formation of mixed dye-surfactant micelles [52]. 

Surfactant solutions critical micelle concentration distribution of reactants among particles surfactant aggregation numbers interface properties and polarity dynamics of surfactant solutions partition coefficients phase transitions influence of additives... 

In the case of non—eutectic systems, the solid phase shows nearly ideal mixing, so that the surfactant components distribute themselves between the micelle and the solid in about the same relative proportions (i.e., both the mixed micelle and mixed solid are approximately ideal). However, in the case of the eutectic type system, the crystal is extremely non-ideal (almost a single component), while the micelle has nearly ideal mixing. As seen in earlier calculations for ideal systems, even though the total surfactant monomer concentration is intermediate between that of the pure components, the monomer concentration of an individual component decreases as its total proportion in solution decreases. As the proportion of surfactant A decreases in solution (proportion of surfactant B increases) from pure A, there is a lower monomer concentration of A. Therefore, it requires a lower temperature or a higher added electrolyte level to precipitate it. At some... 

Danbrow and Rhodes used potentiometric titration data to determine the distribution of benzoic acid (HB) between water and nonionic micelles. The commercial surfactant used has the average formula C16(OC2H4)24. They obtained the following results in 4% surfactant solutions ... 

Marszall (1988) studied the effect of electrolytes on the cloud point of mixed ionic-nonionic surfactant solutions such as SDS and Triton X-100. It was found that the cloud point of the mixed micellar solutions is drastically lowered by a variety of electrolytes at considerably lower concentrations than those affecting the cloud point of nonionic surfactants used alone. The results indicate that the factors affecting the cloud point phenomena of mixed surfactants at very low concentrations of ionic surfactants and electrolytes are primarily electrostatic in nature. The change in the original charge distribution of mixed micelles at a Lxed SDS-Triton X-100 ratio (one molecule per micelle), as indicated by the cloud point measurements as a function of electrolyte concentration, depends mostly on the valency number of the cations (counterions) and to some extent on the kind of the anion (co-ion) and is independent of the type of monovalent cation. 

In a previous study (Deitsch and Smith 1995), the influence of Triton X-100 on Kp for the same Picatinny peat soil was limited to Triton X-100 concentrations above 300 mg/1. At 300 mg/L and below, Triton X-100 did not affect the magnitude of Kp. Since this study has not included the effects of the surfactants on Kp, it will not be possible to identify the mechanism of increased TCE desorption for surfactant solutions that influence the magnitude of Kp. However, for the 30 and 300 mg/L concentrations of Triton X-100, Kp can be assumed to be constant. As a result, the influence of the 30 and 300 mg/L Triton X-100 concentrations on the distribution of rate coefficients can be discerned. 

Figure 2. Distributed rate model simulations of the data obtained from the two CFSTRs flushed with the non-surfactant solutions.

Figure 6. Calculated percentages (based on distributed rate model optimal simulations) of TCE removed from the CFSTRs flushed with the non-surfactant solution, the 30 mg/L Triton X-100 solution, the 300 mg/L Triton X-100 solution, and the 3,000 mg/L Triton X-100 solution. The removal profiles shown are averages of the replicate experiments.

In other cases, several discrete relaxation times or distributions of relaxation times can be found [39]. This is typically the case if the stress relaxation is dominated by reptation processes [42 ]. The stress relaxation model can explain why surfactant solutions with wormlike micelles never show a yield stress Even the smallest applied stress can relax either by reptation or by breakage of micelles. For higher shear rates those solutions typically show shear thinning behaviour and this can be understood by the disentanglement and the orientation of the rod-like micelles in the shear field. 

From this description a well-defined critical concentration emerges as that total amphiphile concentration corresponding to a transition from the monotonic decreasing size distribution function to a size distribution function exhibiting two extrema. This critical concentration corresponds to a surfactant solution with no appreciable amount... 

Fig. 10 a Surface tension of the surfactant solution (stars, right axis) and receding contact angle of the solutions (squares, circles, left axis) on a photoresist layer processed at the threshold dose corrected by the effect of swelling, b Wetting tension y v cos 0 calculated from the values given in (a). The dashed line marks the concentration ceff. Above a, the assumed distribution of the surfactant molecules at various concentrations is drawn schematically... 

Krotov [9] has considered theoretically another case in which the foam column top is irrigated with the surfactant solution and the foam is in contact with the solution through a filter under which a reduced pressure is created. Here, the constancy of foam expansion ratio and border radii along the height of the foam column is fulfilled only when the volumetric flow rate (qo) corresponds to that derived from Eqs. (5.20) or (5.21). If the value of the volumetric flow rate is higher or lower than q0 (q q0), a distribution of n and r by height is observed. For the cases of q > q0 or q < q0 transcendental equations were derived for the... 

In actual use for mobility control studies, the network might first be filled with oil and surfactant solution to give a porous medium with well-defined distributions of the fluids in the medium. This step can be performed according to well-developed procedures from network and percolation theory for nondispersion flow. The novel feature in the model, however, would be the presence of equations from single-capillary theory to describe the formation of lamellae at nodes where tubes of different radii meet and their subsequent flow, splitting at other pore throats, and destruction by film drainage. The result should be equations that meaningfully describe the droplet size population and flow rates as a function of pressure (both absolute and differential across the medium). 

Figure 8 shows an overall view of the raicromodel after simultaneous injection (SI) of gas and surfactant solution (Frame a) and after GDS flooding with only one cycle of gas injection (Frame b). The SI process was filmed during Test 2-5A while the GDS process was filmed during Test 4-15A. Foam flow in the SI process spreads out from the major flow channel more than the GDS flood, and the average size of the bubbles is smaller in the SI case than in the GDS case. The SI process appears to distribute the gas in a more uniform fashion throughout the porous medium when compared to the GDS flood. 

Two sets, i.e., four experiments, of core flow studies are compared. Sets No. 1 and No. 2 were tertiary miscible and immiscible CO2 floods without mobility control. The same core from each set, after plain CO2 injection, was restored to waterflood residual oil saturation and flooded with 0.05% AEGS 25-12 surfactant in brine. There was almost no difference between the oil saturation distributions in the cores between experiments, with the average Sorw values of 37 1 saturation percent in both sets of experiments. CO2 was injected continuously in all experiments at a nominal rate of 1 ft/day. No attempt was made to preform a foam, or to inject alternate slugs of surfactant solution and CO2. 

The results of the last study point out the difficulties in associating specific pesticide exposures to end results. As discussed in Chapter 14, pesticides are almost always applied admixed with solvents, surfactants, and other chemicals that aid in their solution, distribution, and adsorption. More times than not, mixtures of different pesticides are applied to achieve multiple effects. Such pesticide mixtures contain multiple lipophiles and hydro-philes and the mixtures produce effects that are greater than those anticipated from the individual components. Accordingly, it should not be surprising that the teratogenic effects of pesticide mixtures should exceed those of the single species and produce enhanced detrimental outcomes in offspring. 

The enzymatic synthesis of polyphenols was carried out not only in the monophasic solvents but in interfacial systems such as micelles, reverse micelles, and biphasic and Langmuir trough systems, p-Phenylphenol was polymerized in an aqueous surfactant solution to give the polymer with a narrower molecular weight distribution in comparison with that obtained in the aqueous 1,4-dioxane.20... 

The model outlined predicts the equilibrium distribution of HOC in a closed system of soil and micellar surfactant solution as a function of surfactant dose. The model requires values for the parameters Km, /., CMC, Kd,... 

Phenanthrene Solubilization. A model characterizing the distribution of HOC in systems of soil and micellar nonionic surfactant solution was described previously (7). In this model HOC is assumed to partition among three distinct compartments the soil, the micellar pseudophase, and the aqueous pseudophase. The solubilization model accounts for the partitioning of HOC between the micellar pseudophase and the aqueous pseudophase, the increase in apparent HOC solubility associated with nonionic surfactant monomers in the aqueous pseudophase, the sorption of surfactant onto soil, and the increase in fractional organic carbon content of a soil as a result of surfactant sorption. Evaluation of the model with experimental data was described by Edwards et al. (12). 

For DR surfactant solutions with thread-like micelles, Qi proposed a possible DR mechanism in pipe flow as shown in Fig. 16. At rest, thread-like micelles are distributed randomly in the solution. As Arb increases, the thread-like micelles near the wall are extended and start to align along the flow direction because of high wall-shear stress and the solution starts to show DR. Turbulent fluctuations decrease in the radial direction because of the micelle alignment and turbulent energy dissipation is reduced. 

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